Wrist watches have been a part of human culture and attire for quite a few decades, having first become popular in the 1920s. The first few models were simply pocket watches held in place by a strap out of necessity during times of war. Soldiers found it impractical to pull a watch from their pockets in the middle of a battle and started relying on wrist watches more frequently. As wrist watches became popular, their designs improved and evolved over time. Initial designs were entirely mechanical. The next generation models employed electronic mechanisms with quartz oscillators. Digital watches became an item in the 1970s, and since then, various models have surfaced to increase consumer demand, including calculator watches, waterproof watches, camera watches, GPS watches, and so on. Current fashion trends indicate that wrist watches are experiencing a comeback after losing some ground to smart phones and other devices.